One of France's favourite rock stars, Johnny Hallyday, was tonight in an induced coma after doctors in the US performed an emergency operation to remove lesions on his back.

The 66-year-old singer, dubbed the "French Elvis", whose ailing health in recent months has held a devoted nation in suspense, was rushed to hospital in Los Angeles yesterday, suffering complications from earlier surgery in Paris. After briefly waking up and opening his eyes "to recognise his wife", he was put back in an artifical coma to aid his recovery, said his producer, Jean-Claude Camus.

Hallyday, a superstar in France who has sold more than 100m records, has seen a gruelling valedictory tour disrupted this year by repeated health scares. Ever since the revelation over the summer that he had been suffering from colon cancer, his legions of fans have been obsessively following his condition.

Speaking today in Brussels, President Nicolas Sarkozy said he had spoken to the singer's son David on the telephone. "It provokes great emotion in France because he's a much-loved man and, for each of us, he represents a bit of our personal history: memories, feelings, songs, music," he said.

Today, concern over the singer's health was mixed with anger by those who accused his French surgeon of botching the original back operation last month.

Stephané Delajoux, a "surgeon to the stars", whose former clients include the actor and singer Charlotte Gainsbourg, denied any accusation of malpractice. But Camus said the Hallyday family was considering taking legal action over allegedly sloppy surgery.

He claimed on French radio that American doctors had told him they "repaired things" that had allegedly gone wrong with the original surgery.

Laeticia Hallyday, the wife of the ailing star, was "distraught", he added. "[She is] very angry," he said. "He came close to the worst."